I think I'll go with Rhino. I love every aspect of that character in the show. He's one of the funniest villains in this show, if not the funniest. And I love his re-design, with the huge torso and powerful arms, but slim waist and legs; it makes him look much cooler than he does in the comics, IMO. Plus, his voice is superb.
I also have soft spots for Shocker and Silver Sable. I think the changes they made with them from the source materials are for the better (Shocker being Montana from the Enforcers and Sable being a mobster rather than a mercenary) and made them more interesting and fresh.
But as a whole I think that SSM has an excellent rogue gallery. There is no single villain that I dislike, though there are some that I have minor gripes with. Like Venom, who in my opinion became evil too quickly back in Season 1 or Kraven, whose whole feline-mutate look I despise (not because it's unfaithful to the comics - it is faithful to the Ultimate universe - but it just looks bad).
Though I think I've said it before concerning the villains - I'm still waiting for Season 3 and the Hobgoblin to say my final opinion, becuse he's my favorite from the comics.
